1. Field of the Invention
This invention relates to a process cartridge and an electrophotographic image forming apparatus to which the process cartridge is detachably mountable, and further to a developer amount detecting member.
Here, an electrophotographic image forming apparatus includes, for example, an electrophotographic copying machine, an electrophotographic printer (for example, an LED printer, a laser beam printer and the like), an electrophotographic facsimile apparatus, an electrophotographic word processor and so on.
In addition, a process cartridge makes at least one of charging means, developing means and cleaning means, and an electrophotographic photosensitive member integrally into a cartridge that is detachably mountable to an electrophotographic image forming apparatus main body, or makes at least developing means and an electrophotographic photosensitive member integrally into a cartridge that is detachably mountable to an electrophotographic image forming apparatus main body.
2. Related Background Art
Conventionally, in an electrophotographic image forming apparatus using an electrophotographic image forming process, the process cartridge method is adopted that makes an electrophotographic photosensitive member and process means acting on the electrophotographic photosensitive member integrally into a cartridge which is detachably mountable to an electrophotographic image forming apparatus main body. In accordance with the process cartridge method, since the maintenance of the apparatus can be conducted by a user in person and not by a serviceman, the operability can be considerably improved. Hence, the process cartridge method is widely used in electrophotographic image forming apparatuses.
In such an electrophotographic image forming apparatus, means for informing a user of the depletion of the developer, that is, a developer amount detecting apparatus, is provided.
Conventionally, as a developer amount detecting apparatus, there is one that has two electrode rods in a developer container of developing means and detects a change in electrostatic capacitance between the two electrode rods to detect the developer amount.
In addition, Japanese Patent Application Laid-open No. 5-100571 discloses a developer amount detecting apparatus provided with a developer detecting electrode member that is formed by interdigitating two parallel electrodes disposed in parallel on the same plane with a predetermined interval instead of two electrode rods, and that is disposed in the bottom surface of the developer container. This apparatus is for detecting a developer remaining amount by detecting a change in electrostatic capacitance between the parallel electrodes disposed in an flat state.
However, each of the above-mentioned developer amount detecting apparatus merely detects the existence of developer in a developer container, that is, each apparatus can only detect that a developer remaining amount is low immediately before the developer in the developer container is depleted, but cannot detect how much developer remains in the developer container.
On the other hand, if a developer remaining amount in a developer container can be successively detected, it is possible for a user to know the usage status of developer in the developer container and to prepare a new process cartridge at a time for replacement that is extremely convenient to the user.
The present invention has been made in view of the above problems, and therefore has an object thereof to provide a process cartridge, an electrophotographic image forming apparatus and a developer amount detecting member capable of successively detecting a remaining amount of a developer.
It is another object of the present invention to provide a process cartridge, an electrophotographic image forming apparatus and a developer amount detecting member which are provided with a developer amount detecting apparatus capable of successively detecting a remaining amount of the developer in accordance with the consumption of developer in a developer container, and can improve the convenience for a user in using the apparatus.
It is another object of the present invention to provide a process cartridge, an electrophotographic image forming apparatus and a developer amount detecting member that can realize:
(1) miniaturization of a developer amount detecting member and the resulting miniaturization of a cartridge and a developer amount detecting apparatus;
(2) improvement in detection accuracy when a developer amount detecting member is placed within a limited area; and
(3) decrease the cost of parts and the assembly costs.
It is another object of the present invention to provide a process cartridge, an electrophotographic image forming apparatus and a developer amount detecting member having different values of electrostatic capacitance generated by each of a measuring electrode member and a reference electrode member when voltage is impressed on the measuring electrode member and the reference electrode member.
These and other objects, features and advantages of the present invention will become more apparent upon consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.